Obviously there is Gampopa's Jewel Ornament of Liberation, and Tsongkhapa's works are greatly respected. It's interesting that Karmapa is teaching on Tsongkhapa's text, rather than Gampopa's, though obviously this is not unheard of and a good example of being Rimé (as His Holiness OTD always is).

The 8th Karmapa had this to say about Jé Rinpoche:

Mikyö Dorjé wrote:When the teachings of the Sakya, Kagyu, KadamAnd Nyingma sects in Tibet were declining,You, O Tsongkhapa, revived the Buddha's Doctrine,Hence I sing this praise to you of Ganden Mountain.

Are there any other sources for teachings on Lamrim for the Dagpo and/or Shangpa?

"The Sutras, Tantras, and Philosophical Scriptures are great in number. However life is short, and intelligence is limited, so it's hard to cover them completely. You may know a lot, but if you don't put it into practice, it's like dying of thirst on the shore of a great lake. Likewise, it happens that a common corpse is found in the bed of a great scholar." ~ Karma Chagme

"All memories and thoughts are the union of emptiness and knowing, the Mind.Without attachment, self-liberating, like a snake in a knot.Through the qualities of meditating in that way,Mental obscurations are purified and the dharmakaya is attained."